Reading technical paper documents is sometimes frustrating when associated material is cited in the text. For example, readers are expected to access separate paper documents for every reference in a printed bibliography and these are often not readily to hand. Furthermore, this conventional method of citation cannot easily accommodate multimedia materials such as associated audio or video items.
Converting technical documents into electronic form, held in computer memory and to be selectively displayed on a screen, appears to provide one solution to these problems since associated material could then be encoded with the source material and accessed automatically by selecting hyperlinked areas on source pages. On-line help systems work in this way. E-books could work in this way but tend not to. However, the coverage of textual sources represented by on-line help systems is extremely restricted, and both the on-line and e-book approaches require users to relocate their primary reading activity from paper to screen technology.
Over the decades since electronic computers were first invented, office practices have become dominated by them and information handling is now very heavily based in the electronic domain of the computer. The vast majority of documents are prepared, adapted, stored and even read in electronic form on computer display screens. Furthermore, in parallel to this, computer interface technology has advanced from there being a predominantly physical interface with the computer using punched cards, keypads or keyboards for data entry—to the extensive present-day reliance on use of cursor moving devices such as the mouse for interacting with the screen-displayed essentially electronic interface known as the Graphical User Interface (GUI), a paradigm that is in use universally in applications such as Windows®. The Graphical User Interface can be regarded as a virtual interface comprising operator key icons that replace the pushbutton keys of a physical keyboard.
The drive towards handling documents electronically and also representing hardware computer interlaces in a predominantly electronic form has been relentless since, amongst other obvious benefits, software implementations of hardware occupy no space and may be many orders of magnitude cheaper to produce. Nevertheless, electronic versions of documents and virtual interfaces do not readily suit the ergonomic needs of all users and uses. For some tasks, reading included, paper-based documents remain much more user friendly than screen-based documents. Hard copy paper versions of electronic documents are still preferred by many for proofreading or general reviews, since they are of optimally high resolution and flicker-free and less liable to give the reader eye-strain, for example.
In recent years the Xerox Corporation have been in the vanguard of developments to better integrate beneficial elements of paper based documents with their electronic counterpart. In particular they have sought to develop interface systems that heighten the level of physical interactvity and make use of computers to enhance paper-based operations.
Their European patent EP 0,622,722 describes an interactive copying system in which an original paper document lying on a work surface is scanned by an overhead camera linked to a processor/computer to monitor the user's interaction with text or images on the paper document. An action such as pointing to an area of the paper document can be used to select and manipulate an image taken by the camera of the document and the image or a manipulated form of it is then projected back onto the work surface as a copy or modified copy. The Xerox interactive copying system is suited to this role but is not optimally compact, cost efficient and well adapted for other paper-based activities than document copying and transformation. It is not adapted for reading activities.